While this particular model is not described in either the 1885 or 1903 Seibert calatogs, it most likely conforms to the middle polarizing model (mittleres Polarisationsmikrokop) of the period. It features a substage polarizing condenser with a removable top element that is focused using a lever mechanism, an analyzing prism mounted in the tube in a sliding holder, a centerable rotating stage with calibrations in degrees, and a focusing slot which holds a Bertrand lens. An additional slot is provided that accomodates the compensator plates.